Means for insuring the correct positioning of strip stock in progressive punch press dies



Nov. 1, 1955 Q TURNBULL 2,722,274

MEANS FOR INSURING THE CORRECT POSITIONING OF STRIP STOCK IN PROGRESSIVEPUNCH PRESS DIES Filed Feb. 28, 1952 3 Sheets-Sheet 1 5 48 ,g// I/ENTOR:

H16 HGENT N 1955 D. o. TURNBULL MEANS FOR INSURING THE CORRECTPOSITIONING OF STRIP STOCK IN PROGRESSIVE PUNCH PRESS-DIES Filed Feb.28, 1952 5 Sheets-Sheet 2 Willi/01110110011111,

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MEANS FOR INSURING THE CORRECT POSITIONING OF STRIP STOCK IN PROGRESSIVEPUNCH PRESS DIES Filed Feb. 28, 1952 3 Sheets-Sheet I5 im z-n'rae 041000- TMQ/YBl/LL United States Patent MEANS FOR INSURING THE CORRECTPOSITION- ING OF STRIP STOCK IN PROGRESSIVE PUNCH PRESS DIES David 0.Turnbull, Jennings, Mo., assignor to Missouri Automatic ControlCorporation, St. Louis, Mo., a corporation of Missouri ApplicationFebruary 28, 1952, Serial No. 273,904 3 Claims. (Cl. 164-59) Thisinvention relates to means for insuring the correct positioning of stripstock in progressive punch press dies and for causing or permitting thepunch press to be operated only when the stock is so positioned.

An object is the provision of a retractible locking means arranged tointerlock with the strip stock when it has been advanced to the correctposition, thereby to hold the stock in correct position, and to utilizethe movement of the retractible means as it is entered into lockingengagement with the stock to actuate a control device for controllingoperation of the punch press.

A further object is the provision of means for causing the locking meansto be moved between the locking and retracted positions in accordancewith the position of the movable portion of the dies so that the lockingmeans is retracted permitting the stock to be advanced as the dies areparting, so that the locking means is caused to engage the stock beforethe dies have completed their parting movement whereupon this lockengaging movement actuates a press control to a press tripping positionbefore the press has reached top dead center, and so that the lockingmeans is thereafter again retracted slightly before the dies again meet,thereby to permit any necessary minute adjustment of the stock by reasonof stock guide pins carried by the dies.

A further object is to provide in combination with the above, means in aset of progressive punch press dies for blanking the stock, when in theinitial position in the dies, so as to provide a notch or the liketherein adapted to cooperate with the retractible locking means as thestock is advanced to the neXt position.

A further object is to provide in combination with the above, blankingmeans in a set of progressive dies for forming a transverse shoulder inthe strip stock when in the first position and cooperating stop means onthe stationary section of the die whereby stock feeding is stopped whenadvanced to the second position, thereby to permit entry to theretractible locking means.

A further object is to provide a device of the above character which isstructurally included with a set of progressive punch press dies so asto form a unitary assembly adapted to interchangeable use on differentpunch presses.

These and other objects and advantages will become apparent upon readingthe following description in connection with the accompanying drawings.

In the drawings:

Fig. 1 is a view showing progressive operations upon a section of fiatstrip stock as it is fed through a set of conventional five positionprogressive dies which are equipped with means for forming a notch andshoulders in the edge of the stock in the first position.

Fig. 2 is a top view of the retractible locking device shown attached tothe bottom stationary section of the die set and shown in a lockingposition with the locking bar entered into a notch in the strip stock,only a fragmentary portion of the lower die section and strip stockbeing shown;

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Fig. 3 is a cross sectional view of the stripper guide attached to thelower stationary die section and is taken at 33 of Fig. 2;

Fig. 4 is also a cross sectional view through the same stripper guidetaken at 4-4 of Fig. 2;

Fig. 5 is a cross sectional view through the retractible locking deviceand is taken on line 55 of Fig. 2;

Fig. 6 is also a cross sectional view through the retractible lockingdevice and is taken on line 66 of Fig. 2;

Fig. 7 is a side elevation of the retractible locking device with partsthereof sectionalized and is taken on line 77 of Fig. 2;

Fig. 8 is a top view of the retractible locking device with the topcover of the housing removed and is taken on line 88 of Fig. 7;

Figs. 9 and 10 are schematic views of a preferred form of the inventionand are similar except for being in different operative positions. InFig. 9 the dies are shown fully open with the retractible locking deviceengaging the stock and the press control in tripping position, and inFig. 10, the dies are shown partially open on the up stroke with thelocking device retracted permitting the feeding of stock; and

Fig. 11 is a schematic view of the invention shown in connection with aconventional power driven punch press.

The punch press illustrated in Fig. 11 has a frame 101 in which isjournalled an eccentric shaft 102. The shaft 102 has an eccentric 103which vertically reciprocates a head 104. At one end shaft 102 carries afly wheel 105 which freely rotates on the shaft and which is driven bysuitable power means through a belt 106. A conventional self-releasing,self-cocking clutch device is indicated at 107 which, when tripped froma cocked position, engages the shaft and fly wheel for one revolutionand then releases and automatically recocks in a manner well known andunderstood in the art. A clutch tripping device is indicated at 108which takes the form of a pneumatic actuator having a cylinder in whichis fitted a spring returned piston 109. The piston is connected toclutch operating arm 110, and when the piston moves downward underpneumatic pressure, the arm is rotated counterclockwise and trips theclutch. Compressed air for the operation of the actuator is suppliedfrom a suitable source through an air line 111. Interposed in air line111 is a normally closed, electromagnetically operated valve 57 which,when energized, opens to admit compressed air above piston 109. Whenvalve 57 is closed, the piston return spring returns the piston 109 andarm 110 so as to permit recocking of the clutch device. Mounted on thebed 112 of frame 101 is the stationary die section 12 of a set ofprogressive dies, and the cooperating movable section 11 of the die setis carried by the reciprocating head 104.

In Figs. 9 and 10, the upper movable and lower stationary sections ofthe set of progressive punch press dies are shown fragmentarily at 11and 12 respectively. A pair of switches 13 and 14 are attached to andmovable with the upper die section 11 and a pair of switch operatingcams 15 and 16 are attached to the stationary die section 12. Theswitches are provided with operating arms 13a and 14a which follow thesurface of the cams. Switches 13 and 14 are both self-returning, but toopposite operating positions, switch 13 normally returning to a closedposition while switch 14 is normally open. Also attached to the lowerstationary section of the dies is an electromagnetically operatedretractible locking device generally indicated at 17, having areciprocating locking bar 18 guided in the stationary die section 12 andadapted to enter a notch 19 in the edge of the strip stock which isindicated fragmentarily at 20.

The device 17 is attached to the stationary die section 12 by means ofangle brackets 21 and 22 and screws 23,

24, and 25. The brackets 21 and 22 are provided with horizontal andvertical attaching screw slots 26 and 27 respectively to provide forhorizontal and vertical adjustment. The reciprocating locking bar 18 isclosely guided in a rectangular passageway 28 formed partly in the dieportion 12 and partly in a stripper guide 29 which is attached to oneedge of the die section 12 by means of screws 30, see Figs. 2 and 7. Thestripper guide 29 has a groove 31 in its rightwardly extending portion,as shown in Fig. 4, in which the strip stock is guided across the lowerstationary die section. The stripper guide 29 is also provided with acut out portion 32, see Fig. 2, to clear punches (not shown) carried bythe movable die section and which, in a first position blankingoperation, removes that portion of strip stock outlined by the dotdashline in Fig. 2.

The removal of this portion of strip stock provides a notch 19 and ashoulder 33 in one edge of the stock. As the stock is fed leftward afterthe first station operation, the shoulder 33 is adapted to abut ashoulder 35, which is formed on the stripper guide by the cut-out 32.The feeding of stock is thereby positively stopped. It is preferable toalso remove a portion on the opposite edge of the stock in the firstposition blanking operation so as to form a similar shoulder 33a, asshown in Fig. 1, and to also provide a stripper guide (not shown) on theopposite side having a cooperating shoulder similar to 35.

The retractible locking device includes a casing 36 to which thesupporting brackets 22 are attached. Rigidly mounted within the casing36 is an electromagnetic actuator 37 of the solenoid type, having awinding 38 and a reciprocating plunger 39 which is normally springpressed in an outward direction by a spring 40. Pivotally connected tothe outer end of plunger 39, by a clevis and pin arrangement, is anaxially extending shaft 41. The shaft 41 is guided at its inner end in aperforated angle bracket 42 and at its outer end in a perforation 43 inan end wall of the casing 36. The bracket 42, which is attached to thebottom wall of the casing as by screws 44, see Fig. 6, also serves as astop member to limit the outward travel of the plunger 39. The shaft 41extends exteriorly of the casing 36 and has pivotally connected to itsouter end, as by a clevis and pin arrangement, the flat locking bar 18.This clevis pin, which is indicated at 45, extends vertically to a pointslightly above the top of casing 36, as indicated in Fig. 7, and passesthrough a slot 46 in a fiat horizontal bar 47 lying lengthwise acrossthe top of the casing.

The bar 47 extends beyond the right end of casing 36 and has a bent downhandle portion 48. The bar 47 provides a convenient manual means forretracting the looking bar 18 from the notch in the stock to permitsetting up adjustments. The bar 47 is also provided with guides 49 and aspring 50 which is connected at one end to the handle portion 48 and atits other end to the casing and which normally biases the bar 47leftward to a position in which a stop pin 51 therein bears against therear guide 49. In this normal position, the slot 46 permits the freeoperation of the solenoid actuator to a retracted or locking position.

Also rigidly attached within the casing 36 and on opposite sides of theshaft 41, see Fig. 8, is a pair of microswitches 52 and 53. The switchesare of the self-returning type, normally in an open circuit position,and are provided with operating members 5211 and 53a which, whendepressed, cause the switch contacts to be closed. The switches are soarranged that their operating members extend in opposite directions,whereby they are alternately engaged by arms 55 and 56, carried by theshaft 41, as the solenoid actuator is operated to engaging and retractedpositions.

The schematic views 9 and further include the normally closedelectromagnetically operated control valve 57. The device 57 is seriesconnected in a circuit with the switching device 52 by leads 58, 59,and. The

leads 58 and 60 are connected to a plug 61 for convenient detachableconnection to a suitable source of electrical energy.

The retractible locking device actuator winding 38 is series connectedwith the normally closed switch 13 and the normally open switch 14 in afirst energizing circuit as follows: starting with a lead 62, throughthe contacts of switch 13 to a lead 63, through lead 63, through thecontacts of switch 14 to a lead 64, through lead 64 and a lead 65 towinding 38, through winding 38 and through a lead 66. Leads 62 and 66are connected to a plug 67 for convenient detachable connection with asource of energy. Winding 38 is also series connected with the normallyclosed switch 13 and the normally open holding switch 53 in a secondenergizing circuit as follows: starting with lead 62, through thecontacts of switch 13, through lead 63, a lead 68, through the contactsof switch 53, a lead 69, lead 65, through winding 38, and lead 66 backto the plug 67.

In operation In Fig. 9, the dies are shown in their full open positionwith the normally closed switch 13 operated to an open position by thecam 15. The first energizing circuit for winding 38 is broken,therefore, at this point. The normally open switch 14 and the normallyopen holding switch 53 also being in open position, the secondenergizing circuit for the winding 38 is, therefore, also open and thelocking device is, therefore, de-energized and permitted to move towarda locking position under the force of spring 40. Since the pressoperating control device 57 and switch 52 are series connected in anindependent circuit, the device 57 will be energized only When switch 52is closed, and switch 52 will be closed by the engagement of arm 55 onlywhen the retractible locking device is de-energizcd and permitted fulloutward extension by the entry of locking bar 18 into notch 19 as shown.The cam 15 is arranged to open switch 13, thus de-energizing the lockingdevice, during the last portion of the open movement of the dies and,consequently, just before the press crankshaft has reached top deadcenter.

The control valve 57, upon being energized, will cause the press tobetripped and the movable die section 11 will start downward on anoperating stroke. As the die section 11 moves downward, the normallyclosed switch 13 will be permitted to again close. The normally openswitch 14 is still open, however, and the locking device is, therefore,still de-energized and in a locking position. The stock is, therefore,held against longitudinal shift ing by the locking bar 18 as the diesclose. Just before the dies meet, however, the normally open switch 14is closed by the lobe on cam 16 near its lower end. This action causesthe actuator Winding 38 to be energized by the first circuit and thelocking bar 18 to be retracted just before the dies come together. Thisprovision precludes the possibility of any binding action between thelocking bar 18 and "notch 19 which may interfere with the proper seatingof the stock or which may prevent subsequent withdrawal of the bar 18.

During the following upward stroke of the upper die section 11, see Fig.10, the normally open switch 14 is again permitted to open, but theactuator winding 18 is not de-energized by this action because theholding switch 53 is closed, thereby completing the second energizingcircuit described above. The locking device is therefore held in aretracted position during the opening movement of the dies and until thecam 15 again engages switch 13 near the end of the opening stroke. Thestock may be advanced, therefore, by any suitable means such as byconventional feed rollers indicated at 113 during the opening of thedies without interference from the locking 'bar 18.

As the advancing stock being fed to the succeeding position ispositively stopped, as by abutting shoulders 33 thereon with shoulders35 on the stripper guides, it strikes with some impact and there isusually some tendency to rebound, depending, of course, upon theflexibility of the stock and the conventional feeding speed. When theoperation of the feeding device and cam operated switch 13 is properlycoordinated, the locking means will enter the notch as the stock advanceis stopped and rebound is, therefore, prevented. The stock is guidedlaterally in a conventional manner as by grooves 31 in parallel stripperguides.

It is to be understood that a rotary cam carried on the crankshaft ofthe press may be used instead of the vertical reciprocating cams 15 and16, in which case two of the switching devices could be eliminated. Withthe illustrated, preferred arrangement, however, the device is unitarywith a set of punch press dies and is, therefore, convenientlyinterchangeable between presses.

The foregoing description is intended to be illustrative and notlimiting, the scope of the invention being set forth in the appendedclaims.

I claim:

1. The combination with a set of punch press dies having a stationaryand movable section, of an electromagnetically operated stock feedindexing device mounted on the stationary die section and having aspring pressed plunger arranged to enter lateral indexing notchesprovided in the edge of strip stock being fed through the dies when saiddevice is de-energized and arranged to be retracted therefrom when it isenergized, an energizing circuit for said device, a normally closedswitch in said circuit arranged to be moved to an open position as saiddies approach full open position and to again close as said dies startto close, a second normally open switch in said circuit arranged to bemoved to a closed position as said dies approach a closed position andto again open as said dies begin to open, and a shunt circuit aroundsaid second switch including a normally open switch arranged to beactuated to a closed position by means movable with said plunger whensaid device is energized, whereby said plunger is retracted as said diesapproach a closed position and is held retracted until said diesapproach a fully open position and whereby it is released to a stockindexing position as the dies approach fully open position wherein itremains to hold the stock in position until the dies approach a closedposition.

2. The combination with a set of a punch press dies having a stationarysection and a movable section, of a spring pressed stock indexingplunger slidably mounted on said stationary section and arranged toenter lateral notches in the edge of strip stock being fed through thedies, of means including a cam surface carried by one of said diesections and a member on the other of said die sections cooperating withsaid cam surface for causing said plunger to be retracted as saidmovable die section approaches said stationary die section in a dieclosing movement, of means including a member carried by said plungercooperating with a stationary member and rendered operative as saidplunger is moved to a re tracted position to hold said plunger in aretracted position as said movable die section moves oppositely in a dieopening direction, and of means including a second cam surface carriedby one of said die sections and cooperating with a member carried bysaid other die section for rendering said plunger holding meansinoperative as said movable die section approaches a full open dieposition.

3. The combination with a power driven punch press having a frame, apower driven fly wheel, an eccentric shaft, a reciprocating head driventhrough a die closing and a die opening stroke by said eccentric shaft,a selfreleasing, self-cocking, single revolution clutch device forintermittently connecting said fly wheel and shaft for one revolutionwhen tripped, and clutch tripping means which when actuated trips saidclutch, of a set of punch press dies having a stationary portion carriedby said frame, and a movable section carried by said reciprocating head,of a spring pressed, stock indexing plunger slidably carried on saidstationary die section and arranged to suecessively enter longitudinallyspaced lateral notches formed in the edge of strip stock being fedthrough the dies, of means including a cam surface carried by one ofsaid die sections and a member on the other of said die sectionscooperating with said cam surface for causing said plunger to beretracted as said movable die section approaches said stationary die ina die closing stroke, of means including a member carried by saidplunger cooperating with a stationary member and rendered operative assaid plunger is moved to a retracted position to hold said plunger in aretracted position as said movable die section moves oppositely in a dieopening stroke, of means including a second cam surface carried by oneof said die sections and cooperating with a member carried by said otherdie section for rendering said plunger holding means inoperative as saidmovable die section approaches a full die open position, and of meansincluding a member carried by said indexing plunger for actuating saidclutch tripping means when said plunger moves into an indexing positionin a notch in the stock.

References Cited in the file of this patent UNITED STATES PATENTS

